This invention relates to an upward viewing observation window for a hot air balloon. The need for such a window has been demonstrated as the result of accidents which could have been avoided had the pilot of the balloon been able to know that another balloon was descending on top of his balloon. For example, at the 1985 World Ballon Championships, a large number of balloons were launched in poor weather conditions, including winds up to 1000 feet being layered every 150 feet, causing the balloons to fly in many different directions, depending on the particular wind shear in which the balloon was flying.
One particular balloon was in a steep descent. Another balloon directly beneath it was in a steep ascent but could not see because of the very large blind spot caused by the balloon envelope and therefore did not know of the other balloon. The upper balloon hit the lower balloon tearing a hole large enough to allow the entire carriage to enter. The balloons then separated and the lower balloon began a rapid descent from 750 feet altitude. It hit the ground fast enough to cause serious injuries to the pilot.
Accidents like this could be sometimes avoided except for the inability to see above the balloon. Insofar as is known, provision has never before been made for an upward viewing observation window in a balloon.